Influence of Polyelectrolyte (NaCMC) on Surfactant (DTAB) in the Absence and Presence of Methyl Orange Dye in Ethanol–Water Mixed Solvent at Three Different Temperatures

Thermodynamic behavior of dodecyltrimethylammonium bromide (DTAB) in sodium carboxymethyl cellulose (NaCMC) solution with and without methyl orange (MO) dye in the ethanol–water mixture (0, 0.1, 0.2, and 0.3) volume fractions of ethanol at different temperatures by conductivity measurements is studied. The obtained conductivity data suggests that the value of α, CAC, and CMC* for the MO + NaCMC + DTAB system decreases when compared to the NaCMC + DTAB system. MO + NaCMC + DTAB system shows more negative ΔHm0$\mathrm{\Delta}{H}_{\mathrm{m}}^{0}$, ΔGmb0$\mathrm{\Delta}{G}_{\mathrm{mb}}^{0}$, ΔGb0$\mathrm{\Delta}{G}_{\mathrm{b}}^{0}$, and ΔGm0$\mathrm{\Delta}{G}_{\mathrm{m}}^{0}$ and more positive ΔSm0$\mathrm{\Delta}{S}_{\mathrm{m}}^{0}$ values in contrast to the comparable values for the NaCMC + DTAB system. These results demonstrate the thermodynamic feasibility and spontaneity of micellization with MO in the ethanol–water mixture. Nonetheless, as the temperature and the percentage of ethanol in the volume increase, so do the α (degree of dissociation), CAC (critical aggregation concentration), and CMC* values. A valuable insight into the thermodynamic stability, fluidity, solvent structure, polarity of the solvent, and interaction degree in ethanol–water mixture with and without MO may be gained from varying ΔGm0$\Delta G_m^0$ with different solvophobic and solvent parameters. The effect of NaCMC on the interaction and micellization of DTAB in ethanol–water solvents at varying temperatures is investigated conductometrically. The role of methyl orange dye in modifying these interactions is explored. The CAC, CMC, and various thermodynamic parameters are determined and their trends of variations with the temperature and solvent composition are studied.